Synthesis, structure, and application of self-assembled copper(II) aqua complex by H-bonding for acceleration of the nitroaldol reaction on water

Article abstract of DOI:10.1002/asia.200800339

Copper(II) aqua complex 1 has been prepared in a one-pot synthesis. The single crystal X-ray analysis showed that the complex is self-assembled through aqua ligands by H-bond interactions and the copper(II) atoms are pentacoordinated with square pyramidal geometry. Complex 1 has been studied for the acceleration of the nitroalodol reaction on water. It is a clean technological process and the catalyst can be recycled without loss of activity.

Full text of DOI:10.1002/asia.200800339

FULL PAPERS
DOI: 10.1002/asia.200800339
Synthesis, Structure, and Application of Self-Assembled Copper(II) Aqua
Complex by H-Bonding for Acceleration of the Nitroaldol Reaction on Water
Suribabu Jammi, Md Ashif Ali, Sekarpandi Sakthivel, Laxmidhar Rout, and
[
a]
Tharmalingam Punniyamurthy*
Abstract: Copper(II) aqua complex 1 has been prepared in a one-pot synthesis.
The single crystal X-ray analysis showed that the complex is self-assembled
through aqua ligands by H-bond interactions and the copper(II) atoms are penta-
coordinated with square pyramidal geometry. Complex 1 has been studied for the
acceleration of the nitroalodol reaction on water. It is a clean technological pro-
cess and the catalyst can be recycled without loss of activity.
Keywords: C–C coupling · hetero-
geneous catalysis · hydrogen bonds ·
nitroaldol reaction · self-assembly
Introduction
Results and Discussion
The addition of nitroalkanes to carbonyl compounds, known
as the Henry (or nitroaldol) reaction, is a fundamental syn-
The reaction of aldehyde 2 with glycine in the presence of
Et N in EtOH provided Schiff base 3 that was treated with
3
[1]
thetic tool for the formation of carbon–carbon bonds. The
diversity of the transformation of the adducts, such as reduc-
Cu ACHTUNGTNERGUN( OAc) ·1H O in situ to give the copper(II) aqua complex
2 2
1 as a green powder (Scheme 1). During purification with
[2]
[3]
tion to amines, Nef reaction to carbonyl compounds, de-
silica gel column chromatography using 1:9 MeOH/CH Cl2
2
[4]
hydration to nitroalkenes, or nucleophilic displacement, af-
fords numerous applications for this process. In this contri-
bution, we describe the synthesis, structure, and application
of a self-assembled copper(II) aqua complex 1 for the accel-
eration of the nitroaldol reaction on water. The copper(II)
atoms are pentacoordinated with square pyramidal geome-
try. Both the axial aqua ligand, having tetrahedral geometry,
and the equatorial aqua ligand, bearing trigonal geometry,
exhibit intermolecular H-bond interactions with the carbox-
ylate and aqua ligand oxygen of another molecule to afford
the self-assembled structure. Complex 1 floats on water and
catalyzes the nitroaldol reaction to obtain high reaction
yields. The reaction is a heterogeneous process, no additive
is involved and catalyst 1 can be filtered and recycled with-
[5]
out a loss of activity.
[
a] S. Jammi, M. A. Ali, S. Sakthivel, L. Rout, Dr. T. Punniyamurthy
Department Of Chemistry
Indian Institute of Technology Guwahati, Guwahati 781039 (India)
Fax : (+91)361-2690762
E-mail: tpunni@iitg.ernet.in
Scheme 1. Preparation of complex 1.
314
ꢀ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 2009, 4, 314 – 320

as an eluent, complex 1 underwent crystallization to afford
single crystals whose X-ray analysis showed that complex 1
is self-assembled through aqua ligands (Figures 1–3). The
structure. It is well soluble in common organic solvents such
as CH Cl , THF, diethyl ether, CHCl , and toluene, but in-
soluble in water owing to its hydrophobic tert-butyl groups.
Since complex 1 is self-assembled through aqua li-
2
2
3
[6]
[
7,8]
gands,
we were interested to study its catalysis of organic
[9]
reactions on water. First, we studied the addition of nitro-
alkanes to aldehydes. The optimization of the reaction con-
ditions was pursued with 4-nitrobenzaldehyde and nitrome-
thane as model substrates (Table 1). The reaction occurred
Table 1. Reaction of 4-nitrobenzaldehyde with nitroalkanes on water
using 1.
[
a–c]
Entry
Catalyst
CuSO ·5H
Cu(OAc) ·1H
CuCl ·2H
(ClO
(NO
Conv. [%]
1
2
3
4
5
6
7
4
2
O
7
A
H
U
G
R
N
N
2
2
O
14
13
15
16
2
2
O
·6H O
2
·3H
Cu
Cu
1
A
H
U
G
R
N
U
4
)
2
A
H
U
G
R
N
G
3
)
2
2
O
[
d]
>99
no reaction
–
Figure 1. ORTEP diagram of 1 with 50% probability. H-atoms are omit-
ted for clarity.
[
(
4
a] 4-Nitrobenzaldehyde (1 mmol), catalyst 1 (5 mol%), nitromethane
7.5 mmol), and solvent (3 mL) were stirred for 3 h.[b] Determined from
1
00-MHz
H NMR
spectrometer.
[c] Homogeneous
pro-
cess. [d] Heterogeneous process.
efficiently to afford the desired nitroaldol product in high
yield when the substrates were stirred for 3 h with 5 mol%
of 1 on water. It was a heterogeneous process and exhibited
a greater reactivity compared to that of copper salt
(
CuSO ·5H O,
Cu
A
H
U
G
R
N
N
(OAc) ·H O,
CuCl ·2H O,
Cu-
4
2
2
2
2
2
A
H
U
G
R
N
N
ACHTUNGTRNE(NUNG NO ) ·3H O)-catalyzed homogene-
4
2
2
3
2
2
ous systems (Table 2). The reaction on water was accelerat-
ed in comparison to those in organic solvents, CH Cl ,
Figure 2. H-bonded network of 1 viewing down “c” flipping 908 around
an axis perpendicular to the screen.
2
2
CHCl , CCl , ClCH CH Cl, toluene, EtOH, Et O, and THF
3
4
2
2
2
[
9c–d]
(
Table 3).
A control experiment without catalyst showed
no reaction. Similar results were observed for the reaction
of the neat substrates. The reaction of nitromethane was
completed in 3 h with 99% conversion, whereas nitroethane
Table 2. Reaction of 4-nitrobenzaldehyde with nitromethane on water:
screening of copper source.
[
a–c]
Entry
Nitroalkane [mmol]
H
2
O [mL]
Time [h]
Conv. [%]
1
2
3
4
5
6
7
8
9
CH
CH
CH
CH
CH
CH
CH
CH
3
3
3
3
3
3
3
3
NO
NO
NO
NO
NO
NO
NO
NO
2
2
2
2
2
2
2
2
(1)
(2.5)
(5)
(7.5)
(1)
(2.5)
(5)
1
1
1
1
3
3
3
3
–
3
3
3
3
3
3
3
3
3
3
3
15
25
25
30
35
44
77
>99
(7.5)
Figure 3. Self-assembly of 1 with a staircase-like structure.
CH NO (7.5)
3
no reaction
50 [55:45]
15 [54:46]
3
2
[
d]
10
11
12
C
2
H
5
NO
2
(7.5)
(7.5)
(7.5)
30
30
30
[
d]
nC
iC
3
H
7
NO
2
3
H
7
NO
2
no reaction
aqua ligands having tetrahedral (axial) and trigonal (equato-
rial) geometries exhibit intermolecular H-bond interactions
with the oxygen of the carboxylate and the aqua ligand of
another molecule to provide a staircase-like self-assembled
[
(
a] 4-Nitrobenzaldehyde (1 mmol), catalyst 1 (5 mol%), and nitroalkane
1–7.5 mmol) were stirred on water (1–3 mL). [b] Determined from 400-
1
MHz H NMR spectrometer. [c] Heterogeneous process. [d] Diastereo-
meric ratio (syn/anti) determined from 400-MHz H NMR spectrometer.
1
Chem. Asian J. 2009, 4, 314 – 320
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www.chemasianj.org
315

T. Punniyamurthy et al.
FULL PAPERS
Table 3. Reaction of 4-nitrobenzaldehyde with nitromethane using 1:
effect of solvent.
served band shifts suggest that the phenolate oxygen of 1 is
selectively protonated (Figure 5). Thus, the phenolate
oxygen acts as a stronger base compared to the carboxylate
[
a–c]
Entry
Solvent
Conv. [%]
[d]
[10]
1
2
3
4
5
6
7
8
9
H
CH Cl
2 2
CHCl
THF
Toluene
EtOH
2
O
>99
12
14
25
18
40
14
16
20
oxygen under these conditions. Hence, complex 1 may un-
dergo reaction with nitroalkane and aldehyde to provide in-
termediate a that could lead to intermediate b by the proto-
nation of the phenolate oxygen (Scheme 3). An intramolec-
ular 1,2-addition of the nitronate to the aldehyde can give
intermediate c that would complete the catalytic cycle by
the reaction with fresh nitroalkane and aldehyde.
3
CCl
(CH
Et
4
A
H
U
G
E
N
N
2
)
2
Cl
2
2
O
[
a] 4-Nitrobenzaldehyde (1 mmol), complex 1 (5 mol%) and nitrome-
thane (7.5 mmol), and solvent (3 mL) were stirred for 3 h. [b] Deter-
mined from 400-MHz H NMR spectrometer. [c] Homogeneous proc-
1
Conclusions
ess.[d] Heterogeneous process.
Synthesis, crystal structure, and application of a self-assem-
bled copper(II) aqua complex 1 by H-bond interaction are
described for the acceleration of the nitroaldol reaction on
water. It is a heterogeneous process, involves no additive or
base, and catalyst 1 can be recycled without a loss of activi-
ty.
and 1-nitropropane required longer reaction times to pro-
vide the nitroaldols in 50% and 15% conversions, respec-
tively. No reaction was observed with 2-nitropropane.
Next, the reactions of other aldehydes were investigated
with nitromethane (Table 4). Benzaldehyde underwent reac-
tion in 2.5 h with 97% yield. Similar results were observed
with aryl aldehydes having 2-nitro-, 3-bromo-, 4-bromo-, 4-
chloro-, 4-fluoro-, 4-methyl-, 4-methoxy-, and 3,4-dimethoxy
substituents. Aldehydes with electron-withdrawing groups
showed greater reactivity compared to those having elec-
tron-donating groups. These reaction conditions were also
suitable for the reactions of 2-naphthaldehyde and heterocy-
clic aldehydes, 2-pyridinecarboxaldehyde and 2-thiophene-
carboxaldehyde, to afford the nitroaldols in 54–92% yield.
In 2,6-pyridinedicarboxaldehyde, both CHO groups under-
went reaction with 62% yield. Likewise, aliphatic substrates,
propanal, 2-methylpropanal, cyclohexanecarboxaldehyde,
and ethyl glyoxalate underwent reaction to provide the ni-
troaldols in 70–91% yield.
In these reactions, the catalyst 1, the carbonyl compound,
and nitroalkane formed a suspension on water that was
stirred. Once the reaction is completed, catalyst 1 floats on
the surface of the water and the product dissolves into the
water solution. Catalyst 1 can then be filtered quantitatively.
The recovered 1 was reused for the fresh reaction of nitro-
methane with 4-nitrobenzaldehyde for three runs. The reac-
tions occurred to provide the nitroaldol in >99% conver-
sion (Table 5). These studies clearly reveal that catalyst 1 is
recyclable without loss of activity.
Experimental Section
Materials and Methods
Aldehydes, nitroalkanes, glycine (>99%), 2,4-di-tert-butylphenol (98%),
2 2
and Cu ACHTUNGTRENN(NUG OAc) ·1H O (>99%) were purchased from Aldrich. 3,5-Di-tert-
[11]
butyl salicylaldehyde was prepared from 2,4-di-tert-butylphenol. NMR
spectra were recorded on a Varian-400 spectrometer. UV/Vis spectra
were obtained from a Perkin–Elmer Lambda-25 spectrophotometer.
FTIR spectra were obtained from a Nicolet-410 spectrometer. EPR spec-
trum was recorded on a JES-FA-200 spectrometer. X-ray data were col-
lected on a Bruker SMART APEX equipped with CCD area detector
using MoKa radiation. The structure was solved by using SHELXL-97
Gçttingen, Germany. Column chromatography was performed on 230–
4
00 mesh silica gel. Thermogravimetric analysis was recorded on a TGA/
SDTA-851 Mettler Toledo analyzer. Elemental analysis was obtained
from a Perkin–Elmer-2400 CHNS analyzer. ESI-MS was recorded in
MeOH by using a Micromass Quattro II triple quadrupole mass spec-
trometer.
Preparation of Copper(II) Complex 1: 3,5-Di-tert-butyl salicylaldehyde
(234 mg, 1 mmol), glycine (75 mg, 1 mmol), and Et
were refluxed for 12 h in EtOH (5 mL). The reaction mixture was then
treated with Cu(OAc) ·1H O (199 mg, 1 mmol), and stirred over night at
3
N (101 mg, 1 mmol)
A
H
U
G
R
N
N
2
2
ambient temperature. The solvent was evaporated under reduced pres-
sure, and the residue was purified on silica gel column chromatography
using CH Cl and MeOH (9:1) as eluent to afford 1 as green colored nee-
2
2
ꢀ
1
3
ꢀ1
2 2
dles in 85% yield. UV/Vis (CH Cl ): lmax =397 (e=916 mol dm cm ),
83 (e=2669 mol dm cm ); FTIR (KBr): n˜ =3421, 3004, 2961, 2867,
366, 2346, 1633, 1610, 1528, 1459, 1437, 1419, 1379, 1167, 787, 753,
36 cm ; EPR (X-band, MeOH): g
ꢀ
1
3
ꢀ1
2
2
5
The enhanced reactivity of the heterogeneous process
using 1 on water compared to the homogeneous systems in
organic solvents could be attributed to the occurrence of the
reaction at the solid–liquid interface of water droplets
ꢀ1
?
=2.049, g
k
=2.139; elemental analy-
sis: calcd (%) for C17
H 7.03, N 3.66.
H O NCu: C 52.50, H 7.00, N 3.60; found: C 52.56,
27 5
General Procedure for Nitroaldol Reaction
[9b–d]
(
Scheme 2).
The observed experimental results suggest
Aldehyde (1 mmol), nitroalkane (7.5 mmol), and catalyst 1 (5 mol%)
were stirred on water (3 mL) at ambient conditions. The progress of the
reaction was monitored by using TLC. After completion, catalyst 1 was
filtered and the filtrate was extracted with ethyl acetate (2ꢁ10 mL).
Drying (Na SO ) and evaporation of the solvent gave a residue that was
2 4
passed through a short pad of silica gel using ethyl acetate and hexane as
eluent to afford analytically pure nitroaldol product.
that complex 1 acts as a bifunctional catalyst in these reac-
[10]
tions: first, as Brønsted base, and then as Lewis acid. To
confirm this, complex 1 was titrated with HCl in CH Cl
2
2
(
Figure 4). The intensity of the bands at 397 nm and 283 nm
decreased with respect to an increasing concentration of
HCl, and shifted to lower wavelengths at 332 nm and
264 nm, respectively, with clear isobestic points. These ob-
316
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ꢀ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 2009, 4, 314 – 320

Synthesis of Self-Assembled Copper(II) Aqua Complex
Table 4. Reaction of aryl and alkyl aldehydes with nitromethane using 1 on water.
[
a,b]
Entry
Substrate
Time [h]
Product
Yield [%]
97
1
2.5
2
15
81
3
4
5
14
7
76
98
82
15
6
24
72
7
8
12
24
89
75
9
12
24
82
54
1
0
1
1
1
1
2
3
5
92
70
62
20
24
1
1
4
5
6
88
85
12
1
1
6
7
8
91
70
24
[
a] Substrate (1 mmol), complex 1 (5 mol%), and nitromethane (7.5 mmol) were stirred on water (3 mL). [b] Yield of isolated product.
Chem. Asian J. 2009, 4, 314 – 320
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317

T. Punniyamurthy et al.
FULL PAPERS
Table 5. Reaction of 4-nitrobenzaldehyde with nitromethane on water
using 1: recyclability experiments.
[
a,b]
Run
Recovery of 1 [%]
Product [conv.%]
1
2
3
99
97
97
>99
>99
>99
[
[
c]
c]
[
a] 4-Nitrobenzaldehyde (10 mmol), complex 1 (5 mol%), and nitrome-
thane (75 mmol) stirred on water (30 mL) for 3 h. [b] Determined from
1
4
00-MHz H NMR spectrometer. [c] Used recovered 1.
Recycling experiment: The suspen-
sion, which contains 4-nitrobenzalde-
hyde (10 mmol, 1.51 g), catalyst
1
(
(
5 mol%, 0.194 g), and nitromethane
75 mmol, 4.56 g) was stirred for 3 h
on water (30 mL). Catalyst 1 was then
filtered and the filtrate was extracted
with EtOAc (2ꢁ50 mL). The recov-
ered 1 was reused for the new reaction
for three runs. The reactions occurred
without loss of activity to afford the
desired nitroaldol product in >99%
conversion.
Scheme 2. Reaction at the
solid–liquid interface of water
droplets.
Scheme 3. Proposed catalytic cycle.
1
3
2
1
H), 3.28 ppm (d, J=4.0 Hz, 1H); C NMR (100 MHz, CDCl
48.26, 145.24, 127.15, 124.37, 80.83, 70.14 ppm; elemental analysis: calcd
: C 45.29, H 3.80, N 13.20; found: C 45.35, H 3.81,
3
): d=
(
%) for C
8
H
8
N
2
O
5
N 13.22.
[
12b]
2
-Nitro-1-(4-nitrophenyl)propanol:
Colorless solid; m. p.: 92–948C;
ꢀ1
syn/anti ratio 55:45; IR (KBr): n˜ =3448, 1556, 1522, 1344 cm ; syn
isomer: H NMR (400 MHz, CDCl
1
3
): d=8.23–8.19 (m, 2H), 7.58–7.54
(
1
1
m, 2H), 5.16 (d, J=8.4 Hz, 1H), 4.79–4.67 (m, 1H), 3.24 (s, 1H),
1
3
.35 ppm (d, J=7.2 Hz, 3H); C NMR (100 MHz, CDCl
3
): d=148.2,
1
45.5, 128.1, 124.2, 87.9, 75.2, 16.3 ppm; anti isomer: H NMR (400 MHz,
CDCl
3
): d=8.23–8.19 (m, 2H), 7.58–7.54 (m, 2H), 5.53 (d, J=3.2 Hz,
1
H), 4.76–4.67 (m, 1H), 3.24 (s, 1H), 1.46 ppm (d, J=7.2 Hz, 3H);
1
3
C NMR (100 MHz, CDCl
3
): d=148.1, 145.7, 127.2, 124.0, 86.9, 73.0,
: C 47.79, H 4.46,
1
2.0 ppm; elemental analysis: calcd (%) for C H N O
9 10 2 5
N 12.39; found: C 47.87, H 4.45, N 12.42.
ꢀ
2
Figure 4. UV/Vis spectra of 1 (6.6ꢁ10 mm) with an increasing concen-
[
12b]
ꢀ
2
2-Nitro-1-(4-nitrophenyl)butanol:
Colorless solid; m. p. 97–988C; syn/
2 2
tration of HCl (0.0–6.6ꢁ10 mm) in CH Cl .
ꢀ
1
anti ratio 54:46; IR (KBr): n˜ =3460, 1557, 1520, 1345 cm ; syn isomer:
1
H NMR (400 MHz, CDCl
3
): d=8.25 (d, J=8.8 Hz, 2H), 7.57 (d, J=
8
1
.8 Hz, 2H), 5.17–5.13 (m, 1H), 4.61–4.56 (m, 1H), 2.96 (d, J=0.8 Hz,
H), 1.50–1.41 (m, 2H), 0.90 ppm (t, J=0.8 Hz, 3H); C NMR
1
3
(
100 MHz, CDCl
0.51 ppm; anti isomer: H NMR (400 MHz, CDCl
3
): d=148.40, 145.88, 128.04, 124.30, 94.79, 74.49, 24.01,
1
1
8
1
3
9
3
): d=8.25 (d, J=
.8 Hz, 2H), 7.57 (d, J=8.8 Hz, 2H), 5.17–5.13 (m, 1H), 4.61–4.56 (m,
H), 2.96 (d, J=0.8 Hz, 1H), 1.94–1.84 (m, 2H), 0.90 ppm (t, J=0.8 Hz,
1
3
H); C NMR (100 MHz, CDCl
4.33, 73.43, 21.41, 10.24 ppm; elemental analysis: calcd (%) for
: C 50.00, H 5.04, N 11.66; found: C 50.03, H 5.05, N 11.70.
3
): d=148.40, 145.83, 127.46, 128.08,
10 12 2 5
C H N O
[
12c]
2
1
4
1
-Nitro-1-phenylethanol:
Yellow oil; IR (neat): n˜ =3430, 1555,
ꢀ
1
1
347 cm ; H NMR (400 MHz, CDCl ): d=7.39 (m, 5H), 5.46 (m, 1H),
.63–4.48 (m, 2H), 3.03 ppm (s, 1H); C NMR (100 MHz, CDCl
38.33, 129.12, 129.05, 126.10, 81.35, 71.09 ppm; elemental analysis: calcd
3
1
3
3
): d=
(
%) for
C
8
H
9
NO
3
:
C 57.48, H 5.43, N 8.38; found: C 57.50, H 5.44,
N 8.45.
Figure 5. UV/Vis spectra of 1, 1+HCl, and 2,4-di-tert-butylphenol in
[12d]
2
1
8
7
4
-Nitro-1-(2-nitrophenyl)ethanol:
558, 1529, 1348 cm
Yellow oil; IR (neat): n˜ =3585,
ꢀ
2
CH
2
Cl
2
(in all cases the concentration of sample is 6.6ꢁ10 mm).
ꢀ1
1
; H NMR (400 MHz, CDCl ): d=8.07 (d, J=
.0 Hz, 1H), 7.95 (d , J=8.0 Hz, 1H), 7.75 (t, J=7.6 Hz, 1H), 7.56 (t, J=
.6 Hz, 1H), 6.06 (dd, J=7.2, 2.4 Hz, 1H), 4.89 (dd, J=13.6, 2.4 Hz, 1H),
.55 (dd, J=10.0, 5.2 Hz, 1H), 3.39 ppm (s, 1H); C NMR (100 MHz,
): d=147.26, 134.61, 134.34, 129.84, 128.89, 125.16, 80.31,
66.92 ppm; elemental analysis: calcd (%) for C
N 13.20; found: C 45.36, H 3.78, N 13.25.
3
1
3
[
12a]
2
(
-Nitro-1-(4-nitrophenyl)ethanol:
Colorless solid; m. p.: 84–858C; IR
CDCl
3
ꢀ
1
1
KBr) n˜ =3534, 1557, 1521, 1348 cm
;
H NMR (400 MHz, CDCl
3
): d=
8 8 2 5
H N O : C 45.29, H 3.80,
8
.26 (d, J=8.4 Hz, 2H), 7.61 (d, J=8.8 Hz, 2H), 5.60 (m, 1H), 4.58 (m,
318
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Chem. Asian J. 2009, 4, 314 – 320

Synthesis of Self-Assembled Copper(II) Aqua Complex
[
12a]
13
2
1
5
-Nitro-1-(4-chlorophenyl)ethanol:
Yellow oil; IR (neat): n˜ =3430,
H NMR (400 MHz, CDCl ): d=7.38–7.32 (m, 4H),
.44–5.41 (m, 1H), 4.59–4.46 (m, 2H), 3.28 ppm (s, 1H); C NMR
): d=136.79, 134.79, 129.27, 127.49, 81.15, 70.38 ppm;
3
2H), 3.73 ppm (s, 2H); C NMR (100 MHz, CDCl ): d=156.34, 139.15,
ꢀ
1
1
560, 1378 cm
;
3
121.05, 80.24, 70.69 ppm; elemental analysis: calcd (%) for C
C 42.03, H 4.31, N 16.34; found: C 42.08, H 4.30, N 16.45.
9
H
11
N
3
O
6
:
1
3
(
100 MHz, CDCl
3
[12j]
ꢀ1
1-Nitro-2-butanol:
1
Colorless oil; IR (KBr): n˜ =3449, 1556, 1385 cm
H NMR (400 MHz, CDCl
d, J=4.8 Hz, 1H), 1.59 (m, 2H), 1.04 ppm (t, J=6.8, 8.4 Hz, 3H);
C NMR (100 MHz, CDCl
analysis: calcd (%) for
C 40.41, H 7.63, N 11.84.
;
elemental analysis: calcd (%) for C
found: C 47.73, H 4.02, N 7.01.
8
H
8
NO
3
Cl: C 47.66, H 4.00, N 6.95;
3
): d=4.46–4.38 (m, 2H), 4.25 (m, 1H), 2.54
(
[
12e]
13
2
1
7
1
8
-Nitro-1-(4-bromophenyl)ethanol:
Yellow oil; IR (neat): n˜ =3445,
H NMR (400 MHz, CDCl ): d=7.54–7.52 (m, 2H),
.30–7.25 (m, 2H), 5.45–5.42 (m, 1H), 4.59–4.46 (m, 2H), 3.00 ppm (s,
3
): d=80.53, 70.10, 27.04, 9.74 ppm; elemental
NO C 40.33, H 7.62, N 11.76; found:
ꢀ
1
1
558, 1349 cm
;
3
C
4
H
9
3
:
1
3
H); C NMR (100 MHz, CDCl
3
): d=137.57, 132.71, 128.15, 123.49,
NO Br: C 39.05,
[12d]
3
1
1
-Methyl-1-nitro-2-butanol:
Colorless oil; IR (neat): n˜ =3420, 1558,
H NMR (400 MHz, CDCl ): d 4.49–4.38 (m, 2H), 4.11 (m,
H), 2.48 (s, 1H), 1.83–1.78 (m, 1H), 1.01–0.98 ppm (m, 6H); C NMR
): d=79.46, 73.53, 31.94, 18.66, 17.66 ppm; elemental
1.44, 70.85 ppm; elemental analysis: calcd (%) for C
H 3.28, N 5.69; found: C 39.12, H 3.26, N 5.73.
8
H
8
3
ꢀ1
1
380 cm
;
3
1
3
[
12f]
2
1
2
2
1
-Nitro-1-(4-fluorophenyl)ethanol:
557, 1511, 1342 cm
Yellow oil; IR (neat): n˜ =3425,
H NMR (400 MHz, CDCl ): d=7.39–7.37 (m,
H), 7.10–7.05 (m, 2H), 5.46–5.42 (dd, J=3.2, 5.2 Hz, 1H), 4.59–4.45 (m,
(100 MHz, CDCl
3
ꢀ
1
1
;
3
analysis: calcd (%) for C
C 45.18, H 8.36, N 10.50.
5
H
11NO
3
: C 45.10, H 8.33, N 10.52; found:
1
3
[12j]
H), 2.90 ppm (s, 1H); C NMR (100 MHz, CDCl
16.36, 116.15, 81.33, 70.54 ppm; elemental analysis: calcd (%) for
NO F: C 51.90, H 4.36, N 7.56; found: C 51.95, H 4.37, N 7.62.
-Nitro-1-(3-bromophenyl)ethanol:
3
): d=128.02, 127.94,
2-Nitro-1-cyclohexylethanol:
1384 cm ; H NMR (400 MHz, CDCl ): d=4.51–4.40 (m, 2H), 4.10–4.09
(m, 1H), 2.51–2.49 (d, J=5.2 Hz, 1H), 1.85–1.03 ppm (m, 11H);
3
C NMR (100 MHz, CDCl ): d=79.52, 73.05, 41.63, 29.03, 28.17, 26.29,
Yellow oil; IR (neat): n˜ =3432, 1550,
ꢀ
1
1
3
C
8
H
8
3
[
12 g]
13
2
1
Colorless oil; IR (neat): n˜ =3437,
557, 1343 cm ; H NMR (400 MHz, CDCl ): d=7.58 (s, 1H), 7.50–7.47
ꢀ
1
1
8 3
26.10, 25.96 ppm; elemental analysis: calcd (%) for C H15NO : C 55.47,
3
(
3
1
m, 1H), 7.33–7.25 (m, 2H), 5.45–5.42 (m, 1H), 4.60–4.48 (m, 2H),
H 8.73, N 8.09; found: C 55.52, H 8.79, N 8.17.
1
3
[12k]
.1 ppm (s, 1H); C NMR (100 MHz, CDCl
29.25, 124.73, 123.17, 81.14, 70.35 ppm; elemental analysis: calcd (%)
NO Br: C 39.05, H 3.28, N 5.69; found: C 39.02, H 3.29, N 5.75.
-Nitro-1-(4-methylphenyl)ethanol:
3
): d=140.53, 132.14, 130.74,
2-Hydroxy-3-nitropropanoic acid ethyl ester:
Colorless oil; IR (neat):
ꢀ
1
1
n˜ =3417, 1555, 1385 cm ; H NMR (400 MHz, CDCl ): d=4.75–4.74 (m,
3
for C
8
H
8
3
2H), 4.60 (m, 1H), 4.37–4.28 (m, 2H), 3.35 (s, 1H), 1.31 ppm (t, J=
[
12b]
13
2
1
5
2
1
Colorless oil; IR (neat): n˜ =3422,
H NMR (400 MHz, CDCl ): d=7.29–7.19 (m, 4H),
.44–5.41 (dd, J=9.6, 2.4 Hz, 1H), 4.63–4.46 (m, 2H), 2.90 (s, 1H),
7.2 Hz, 3H); C NMR (100 MHz, CDCl
3
): d=170.90, 77.01, 67.66, 62.88,
ꢀ
1
1
557, 1380 cm
;
3
13.93 ppm; elemental analysis: calcd (%) for C
N 8.59; found: C 36.86, H 5.55, N 8.65.
5 9 5
H NO : C 36.81, H 5.56,
1
3
.36 ppm (s, 3H); C NMR (100 MHz, CDCl
29.84, 126.05, 81.44, 71.06, 21.33 ppm; elemental analysis: calcd (%) for
: C 59.66, H 6.12, N 7.73; found: C 59.70, H 6.10, N 7.80.
3
): d=139.06, 135.36,
9 3
C H11NO
[
12a]
2
1
2
3
-Nitro-1-(4-methoxyphenyl)ethanol:
Yellow oil; IR (neat): n˜ =3445,
H NMR (400 MHz, CDCl ): d=7.31 (d, J=8.8 Hz,
H), 6.91 (d, J=8.8 Hz, 2H), 5.40 (d, J=9.2 Hz, 1H), 4.61–4.44 (m, 2H),
Acknowledgements
ꢀ
1
1
559, 1377 cm
;
3
This work was supported by the Department of Science and Technology,
New Delhi, and Council of Scientific and Industrial Research, New
Delhi. We are grateful to Mr. Babulal Das for crystal analysis. We thank
Dr. Chivukula V. Sastri and Dr. Biplab Mondal for discussions.
1
3
3
.79 (s, 3H), 2.73 ppm (d, J=3.2 Hz, 1H); C NMR (100 MHz, CDCl ):
d=160.17, 130.45, 127.48, 114.55, 81.45, 70.84, 55.55 ppm; elemental anal-
ysis: calcd (%) for C
H 5.63, N 7.16.
9 4
H11NO : C 54.82, H 5.62, N 7.10; found: C 54.90,
[
1k]
2
3
3
1
1
-Nitro-1-(3,4-dimethoxyphenyl)ethanol:
Yellow oil; IR (neat): n˜ =
H NMR (400 MHz, CDCl ): d=6.92–6.82 (m,
H), 5.39–5.37 (m, 1H), 4.62–4.46 (m, 2H), 3.87 (s, 6H), 3.22 ppm (s,
ꢀ
1
1
570, 1565, 1348 cm
;
3
[1] a) S. U. Pandya, R. S. Dickins, D. Parker, Org. Biomol. Chem. 2007,
5, 3842; b) Y. Sohtome, N. Takemura, K. Takada, R. Takagi, T.
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1
3
H); C NMR (100 MHz, CDCl
08.94, 81.49, 70.97, 56.04 ppm; elemental analysis: calcd (%) for
: C 52.86, H 5.77, N 6.16; found: C 52.90, H 5.76, N 6.25.
3
): d=149.42, 130.93, 118.45, 111.36,
10 5
C H13NO
[
12h]
2
1
(
3
1
7
-Nitro-1-naphthylethanol:
Yellow oil; IR (neat): n˜ =3422, 1555, 1512,
ꢀ
1
1
342 cm ; H NMR (400 MHz, CDCl ): d=7.88–7.84 (m, 4H), 7.54–7.51
m, 2H), 7.47–7.44 (m, 1H), 5.62–5.59 (m, 1H), 4.71–4.56 (m, 2H),
.11 ppm (s, 1H); C NMR (100 MHz, CDCl
33.42, 129.25, 128.30, 128.03, 126.96, 126.92, 125.56, 123.44, 81.44,
1.38 ppm; elemental analysis: calcd (%) for C12 : C 66.35, H 5.10,
3
1
3
3
): d=135.66, 133.64,
2
007, 2561; h) J. Boruwa, N. Gogoi, P. P. Saikia, N. C. Barua, Tetrahe-
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125, 12692; j) T. Marcelli, R. N. S. van der Haas, J. H. van Maar-
seveen, H. Hiemstra, Angew. Chem. 2006, 118, 943; Angew. Chem.
Int. Ed. 2006, 45, 929; k) B. M. Trost, V. S. C. Yeh, Angew. Chem.
H11NO
3
N 6.45; found: C 66.43, H 5.12, N 6.46.
[
12a]
2
1
4
1
-Nitro-1-(2-pyridyl)ethanol.
Yellow oil; IR (neat): n˜ =3349, 2917,
H NMR (400 MHz, CDCl ): d=8.58–8.57 (d, J=
.8 Hz, 1H), 7.79–7.75 (m, 1H), 7.45 (d, J=6.0 Hz, 1H), 7.32–7.26 (m,
ꢀ
1
1
557,1432,1381 cm
;
3
2
002, 114, 869; Angew. Chem. Int. Ed. 2002, 41, 841; l) C. Palomo,
1
3
H), 5.48–4.80 (m, 1H), 4.80–4.62 (m, 2H), 4.42 ppm (s, 1H); C NMR
): d=157.17, 148.93, 137.75, 123.70, 121.18, 80.79,
0.64 ppm; elemental analysis: calcd (%) for C : C 50.00, H 4.80,
M. Oiarbide, A. Laso, Angew. Chem. 2005, 117, 3949; Angew. Chem.
Int. Ed. 2005, 44, 3881; m) J. Gao, R. A. Zingaro, J. H. Reibenspies,
A. E. Martell, Org. Lett. 2004, 6, 2453; n) J. Tian, N. Yamagiwa, S.
Matsunaga, M. Shibasaki, Angew. Chem. 2002, 114, 3788; Angew.
Chem. Int. Ed. 2002, 41, 3636; o) T. Arai, M. Watanabe, A. Yanagi-
sawa, Org. Lett. 2007, 9, 3595; p) M. Bandini, M. Benaglia, R. Sinisi,
S. Tommasi, A. Umani-Ronchi, Org. Lett. 2007, 9, 2151; q) Y. Xiong,
F. Wang, X. Huang, Y. Wen, X. Feng, Chem. Eur. J. 2007, 13, 829;
r) C. Christensen, K. Juhl, K. A. Jorgensen, Chem. Commun. 2001,
(
100 MHz, CDCl
3
7
7 8 2 3
H N O
N 16.66; found: C 50.09, H 4.81, N 16.70.
[
12i]
2
1
1
(
1
-Nitro-1-(2-thiophenyl)ethanol:
Yellow oil; IR (neat): n˜ =3416, 1618,
H NMR (400 MHz, CDCl ): d=7.33–7.31(m,
H), 7.06–7.04 (m, 1H), 7.01–6.99 (m, 1H), 5.72–5.70 (m, 1H), 4.73–4.57
ꢀ1
1
557, 1415, 1380 cm
;
3
ACHTUNGTRENNUNG
1
3
m, 2H), 3.00 ppm (d, J=4.4 Hz, 1H); C NMR (100 MHz, CDCl
41.59, 127.37, 126.25, 125.19, 81.01, 67.24 ppm; elemental analysis: calcd
%) for C NO S: C 41.61, H 4.07, N 8.09; found: C 41.68, H 4.05,
3
): d=
(
6
H
7
3
2
222.
N 8.17.
[
2] a) F.-M. Kiess, P. Poggendorf, S. Picasso, V. Jager, Chem. Commun.
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1
7
,6-Pyridine-di-2-nitro-1-ethanol: Yellow oil; IR (neat): n˜ =3394, 1554,
380 cm ; H NMR (400 MHz, CDCl
.52 (d, J=8.0 Hz, 2H), 5.44 (m, 2H), 4.84–4.80 (m, 2H), 4.71–4.65 (m,
ꢀ
1
1
3
): d=7.87–7.83 (t, J=8.0 Hz, 1H),
Chem. Asian J. 2009, 4, 314 – 320
ꢀ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Chem. Asian J. 2009, 4, 314 – 320